The present invention relates generally to a method and apparatus for reducing glare. The present invention is primarily directed to a glare reduction device for aiding a driver of an automobile when encountering a glare producing light source in the horizon such as oncoming headlights or the sun at either dusk or dawn.
Glare producing light sources reduce the visual acuity of observers. That is, the glare reduces the observers' ability to see and understand visual information which is characterized by a loss of sensitivity and increased response time of the retina and the contraction of the pupils. See John V. Forrester et al., The Eye (WB Saunders Co. Ltd. 1996). This natural behavior of the human eye causes a problem in viewing anything other than the glare producing light source because the other visual information which is important to the observer is not detected as well by the eye. In the case where the observer is a driver of an automotive vehicle in the presence of glare produced by oncoming headlights or the sun at either dusk or dawn, the glare can cause "blindness". That is, the driver will observe the glare but the roadway and other conditions in the driver's view will appear black or darker even though these conditions are illuminated by the headlights of the driver's automobile. An analogous situation occurs in taking photographs with an automatic camera with a bright light source in the background. The camera adjusts the exposure based upon the bright light source resulting in a photograph that is underexposed with respect to the other visual information that is intended to be recorded. Devices which are intended to attenuate glare producing light reduce the intensity of the light from the glare producing light source in order to prevent the viewer's pupils from contracting thereby increasing the visibility of the other critical visual information.
Various types of devices for reducing glare are known in the art. Generally, most glare reduction devices use either tinted elements, polarized elements, or a combination of both tinted and polarized elements as a light filter to reduce the glare. Most of the glare reduction devices which rely completely on polarizing the light from oncoming headlights contemplate that the headlights of the approaching vehicle will be equipped with polarized elements such that the light emitted from the approaching vehicle is initially polarized. U.S. Pat. No. 2,087,795 to Chubb, U.S. Pat. No. 2,301,126 to Kriebel, U.S. Pat. No. 2,237,565 to Land, U.S. Pat. No. 2,334,446 to Serrell, U.S. Pat. No. 2,475,921 to Smith, and U.S. Pat. No. 3,026,763 to Marks. Glare reduction devices generally include windshields, visors, and eyeglasses equipped with light filters designed to reduce the glare.
U.S. Pat. No. 5,252,997 to Christenbery discloses a visual aid for night driving. The visual aid is a pair of glasses which includes a glare reduction arrangement 18. With reference to FIG. 1, the glare reduction arrangement 18 has a horizontal glare reduction portion 20 and a vertical glare reduction portion 22 located in the lower left hand quadrant as the wearer looks through the glasses. The intended purpose of the horizontal portion 20 is for the reduction of glare from oncoming headlights of automobiles. The vertical glare reduction portion 22 is provided to reduce the glare caused by headlights of automobiles approaching from the rear which are reflected by a driver's side mirror. The horizontal glare reducing portion is tinted and may be polarized, and the vertical glare reducing portion is preferably opaque, but may be polarized or tinted. The patent, however, does not disclose or suggest equipping eyeware with a glare reduction portion to account for the approach pattern of oncoming headlights.
U.S. Pat. No. 3,026,763 to Marks discloses a windshield which uses light polarization to eliminate the glare from oncoming headlights. The Marks technology requires that the oncoming headlights be equipped with structures to polarize light in the vertical plane. The windshield includes a multi-layered light polarizing structure extending across the top portion of the windshield and curved downwardly at both the left and right sides of the windshield. The polarization is graduated such that the polarization increases progressively from the bottom of the polarizing structure to the top.
U.S. Pat. No. 2,475,921 to Smith discloses a glare reduction filter utilizing polarized light for the reduction of the glare from oncoming headlights. The Smith arrangement requires that either the windshield or viewing visor include a polarizing element, and that the headlights of the oncoming vehicle be equipped with a light-polarizing headlight shield for cooperation with the polarizing element within the windshield or visor of the driver's automobile.
U.S. Pat. No. 2,301,126 to Kriebel discloses a glare elimination apparatus for reducing the glare from light sources originating from within an automotive vehicle. The apparatus uses two polarized elements for reducing the glare. The apparatus includes a transparent light-polarizing screen located behind the driver and goggles equipped with polarizing elements.
U.S. Pat. No. 2,237,565 to Land discloses an apparatus for use in antiglare devices employing polarized light. The Land apparatus is intended to improve antiglare devices which require polarized light elements in both the headlights of the oncoming automotive vehicles and the windshields or visors of the vehicle. The improvement addresses a problem created by the inclusion of plastic sheets in a windshield to make them shatter-proof by adding a third polarizing element to correct distortion caused by the plastic sheets.
U.S. Pat. No. 2,087,795 to Chubb discloses a vehicle lighting system for reducing the glare from oncoming headlights. The lighting system contemplates that all automobiles will be equipped with polarized headlights and that the drivers of their respective automobiles will wear goggles that include polarized elements to reduce or eliminate the oncoming headlight glare. The polarized elements are located in the upper portion of the goggles in the belief that the driver will instinctively use the polarized portion of the goggles in the presence of oncoming headlights. The Chubb '795 patent also discloses that as an alternative to the polarized light, colored light and goggles with colored elements could similarly be used. Chubb indicates that the windshield could also include polarizing elements in lieu of goggles.
U.S. Pat. No. 1,577,527 to Hoyt discloses a tinted windshield for reducing the glare from oncoming headlights.
U.S. Pat. No. 2,334,446 to Serrell discloses polarizing goggles for reducing headlight glare and road glare during daytime driving. The upper segment of goggle lenses include a polarized element intended to cooperate with polarizing devices included in the headlights of the oncoming automotive vehicles. The lower segment of the goggle lenses include a polarized element intended to reduce the glare from road surfaces during daytime driving.
U.S. Pat. No. 2,773,422 to Flynn et al. discloses sunglasses which include a plurality of polarized elements. The sunglasses are configured to allow polarized elements to be rotated with respect to each other for regulating the passage of light through the glasses.
U.S. Pat. No. 2,005,426 to Land discloses polarizing sunglasses which include two polarized elements for each eye. The sunglasses are configured to allow the two polarized elements to be rotated with respect to each other to adjust the amount of light that may pass through the lenses.
U.S. Pat. No. 1,584,041 to Shaver discloses an eye shield for protecting the eyes of a driver of an automobile from the glare of oncoming headlights. The eye shield includes lenses having a tinted portion which are capable of being rotated within the frames so that the tinted portion may be positioned at either the bottom or the top of the frame.
U.S. Pat. No. 950,255 to Alles discloses and eye shade for protecting the eyes of workman in the metal and glass working trades. The eye shade includes a translucent portion at the upper portion of the glasses.
U.S. Pat. No. 5,372,504 to Buechler discloses clip-on eyewear for pilot training which has an opaque region on each lens.
U.S. Pat. No. 4,698,022 to Gilson discloses goggles for pilot training which include a region having a translucency selected for varying visibility distances.
Each of the methods and apparatus described above has inherent shortcomings which detract from convenience of use and/or efficacy of attenuating glare without diminishing visual information, and it is an object of the present invention to overcome such shortcomings and to provide an improved method and apparatus for restricting glare while minimizing loss of visual information.